The length of Lucan Battison's hair has landed another student in hot water.

A girl from Sacred Heart College - whose father suspended Lucan - posted foul-mouthed tweets about the St John's College boy, calling him "a sack of s. .t" and "beyond pathetic" for "taking my dad and principal of St John's to court".

The girl's father chaired the St John's disciplinary subcommittee that suspended Lucan from the Hastings college on May 22. The school lifted the suspension on May 30, allowing him to return if he cut his hair first. Lucan offered to tie his hair back, but this was unacceptable to the school.

The family intend to go to court on Monday to seek a judicial review of the school's decision.

The girl from Sacred Heart, which is St John's sister school in Napier, took to Twitter encouraging her friends to watch the family "pleading their case" on Seven Sharp on Monday night.

In the tweets, which her father said had since been deleted, she wrote: "shame lucan you f. . .ing f. . . .t, have fun trying to get the school to let ya keep your hair long".